A procedure for on-farm evaluation of East Coast Fever management in dairy cattle systems: a case of coastal lowlands of Kenya

C B Wasike

Department of Animal Science, School of Agriculture and Food Security, Maseno University, P.O. Box 333, 40105 Maseno.
wasikebwire@yahoo.co.uk

Abstract

A study was designed to develop procedure for valuation of East Coast Fever management through a factor based East Coast Fever management index. It quantified costs of East Coast fever management factors and revenue loss as result of East Coast fever incidence(s) within farms, for use as input variables by insurance firms and livestock compensation schemes. Annual estimates of the cost of East Coast fever management which could be used in determination of premiums and compensation by livestock insurance firms are presented.

Keywords: curative treatment, dairy systems, disease costs, prophylactic treatment, revenue losses

Introduction

Livestock insurance is a recent development in Kenya (Otieno et al 2006). The insurance premiums are determined by the highest sources of risks of loss (Larson et al 2003; Mohammed and Ortman 2005). Risks are partitioned by area with drought having great importance in arid and semi-arid areas whereas diseases such as East Coast Fever have greater importance in the pastoral areas of the lower rift valley and the coast (Otieno et al 2006). The risk index when insuring animals in the coastal lowlands is highest for East Coast fever due to the prevalence of the disease and associated mortalities, making it a critical component in calculation of insurance premiums and compensation. Quantified estimates of expenses and losses attributed to East Coast fever are important in valuation of the risk index for East Coast Fever. This paper presents a method for quantifying costs of East Coast fever management and its valuation of animals by insurance firms in the coastal lowlands of Kenya.

Materials and methods

Data source and animal management

Data for this study was collected from two privately owned commercial farms (Farms A and B; names withheld as requested by the producers) in Kilifi District of Kilifi County in the coastal lowlands of Kenya. The farms are situated approximately 5km and 30km, south of Kilifi town, respectively and fall within the same agro-ecological zone (coastal lowland I). The region is characterized by an average amount of rainfall, and high temperatures making it a high pressure belt for tick multiplication.

The two farms kept purebred exotic breeds (Holstein Friesian interspaced with Ayrshire, Brown Swiss, Jersey and Guernsey, and their crossbred genotypes with the Sahiwal). Management of animals was within paddocks sowed with Rhodes grass pasture. Supplementary feeding was done for lactating animals in all farms although the level was varied between farms.

The farms adopted prophylactic measures to control endemic diseases and curative measures to treat animals whenever clinical symptoms of disease were reported. The most common diseases reported on the farms were East Coast fever, Anaplasmosis and Trypanosomosis. The farms had a foot bath at the entrance of the farm and practiced controlled access to the livestock units. Control of external parasites was by spraying in farm A and dipping in farm B. Internal parasites especially the helminthes were controlled by routine drenching using antihelmintics. Table 1 presents characteristics of the farms that were used as variables for computations.

Data collection

Semi structured Interviews were conducted with livestock managers in the respective farms using an interview schedule that had open ended questions to get the baseline information on East Coast fever management. The questions probed the producers on prevalence of East Coast fever on the farm, morbidity and mortality rates, control and curative management practices instituted, their costs and the factors that influence choice of a management practice, milk losses as well as losses due to death of animals and, the type and cost of labour. In addition, herd averages for cow productivity, value of lactating cows and heifers, as well as average milk prices were also probed (Table 2).

Computational procedure for calculating the monetary value of East Coast fever management

The cost of East Coast fever management was classified into two categories namely a). Successfully managed cases i.e. East Coast fever infected animals treated to heath and b). Fatal cases i.e. when the animal succumbed to East Coast fever. Implications of anticipation and/or incident of East Coast fever include cost of disease management and revenue losses whose sum gives the value of East Coast fever management. Therefore the value of East Coast fever management could be computed as:

Value of East Coast fever Management (VoEM) = Cost of Disease Management (CoDM) + Revenue Losses (RL)

Calculation of Cost of Disease Management (CoDM)

Cost of disease management (CoDM) was computed as the sum of the costs of prophylactic and curative strategies of disease management, i.e.

CoDM = cost of prophylactic management (CoPM) + cost of curative management (CoCM)

1. Computation of annual costs of prophylactic management per animal

The key factors of production whose costs have to be computed for prophylactic management of East Coast fever include labour and the acaricide used in the dip or spray race. This is computed as:

Annual CoPM per animal = (fixed costs (cost of disease management infrastructure e.g. dips and spray races, accounting for depreciation) + variable costs (Cost of Labour + Cost of dip wash/ spray race acaricide + cost of water)) ÷ Herd size

a) Annual Labour costs for dipping/spraying (LaCD)

LaCD= (Cost of Permanent staff (herders) per dipping/spraying session (CoPS) + cost of temporary staff per dipping/spraying session (CoTS))× number of dip sessions per annum

i. Cost of permanent staff per dip/spray session (CoPS)

CoPS= Number of staff × length of dip or spray session (hours)× Cost of unit Man hour

Cost of unit man hour = monthly pay÷ 30days÷8 hours per day

ii. Cost of temporary staff engaged per dip/spray session (CoTS)

CoTS= No. of staff × length of Dip or spray session (hours)× cost of unit Man hour

b) Annual Cost of dip/spray race acaricide (CoDA)

CoDA = cost of base acaricide(CoBA) + cost of top-up acaricide (CoTA)

i. Annual CoBA = Volume of base acaricide × cost per unit volume of acaricide

ii. Annual CoTA = Volume of top up acaricide per session × cost per unit volume of acaricide × number of dip/spray sessions per annum

c) Annual cost of water used for dipping/spraying (CoWD)

This was computed as a product of the cost per unit volume of water and the volume of water used per year for dipping/ spraying, i.e.

CoWD = volume of water per year × cost per unit volume of water

2. Computation of annual costs of curative management per animal

Curative management is a function of morbidity of the disease, cost of diagnosis and medicines as well as cost of veterinary care. Morbidity is expressed as a proportion of herd size. Therefore costs of curative management are presented relative to the herd size. As a result, annual relative herd costs of curative management of East Coast fever per animal (CoCM) were computed as:

CoCM = (cost of treatment per case × average annual morbidity) + (cost of lab diagnosis × Average annual morbidity)

Cost of treatment is the sum of the cost of the drugs and cost of veterinary service/care.

Average annual morbidity = number of disease incidences reported ÷ the herd size

Calculation of revenue losses (RL)

Revenue losses attributable to East Coast fever could be as a result of loss revenue from drop milk production when milking animal suffers from ECF, which could be well over three weeks, milk loss due to withdrawal as a result of treatment (on average most drugs have withdrawal period of 72 hours) and the value of the animal in the event of mortality. Therefore the revenue lost was a function of East Coast fever incidences and mortalities reported in the herd, and the unit price of milk and animal, respectively. East Coast fever incidence is expressed as a proportion of herd size, therefore, the revenue lost per animal is relative to the herd size computed as:

Annual relative herd RL per animal = annual relative herd revenue loss from milk (MRL) per animal + market value of animal in case of mortality

Annual relative herd revenue loss from milk (MRL) per animal = (milk yield per cow per day ×withdrawal period(days) + ((milk production× %drop in milk production) × convalescence period))× average morbidity× price of milk

Milk yield per cow per day = 305 Lactation milk yield÷ 365 days

Annual relative herd revenue lost due to mortality per animal = Market price of the animal × average herd mortality

Results and discussion

Factors of production that influence East Coast fever management across farms and their associated costs are presented in Table 3. Absolute costs of prophylactic management were highest in farm A. However relative to the herd size, cost of prophylactic management was highest in farm B as depicted in Table 4. The high costs in farm B could be attributed to the method of prophylactic management used. The farm uses a plunge dip for tick control. Given the standards in dimensions of the dip and guidelines on frequency of acaricide replenishment, a plunge dip is economical with large herds than small herds; therefore farm B would reduce its costs of prophylactic management by increasing the herd size. Relative to spraying, dipping of animals was a cheaper option of prophylactic management.

The coastal region is one of the areas in Kenya where East Coast fever is endemic with a morbidity rate of about 57% -79% in adult animals (Gichohi et al 2012). Relative to the region, the morbidity rates reported in this study are low owing to the prophylactic measures undertaken by the farms. A look at morbidity of East Coast fever in a year (data not shown) shows high incidences of East Coast fever during wet seasons. This could be attributed to the acaricide being washed off the body of cattle by rain water thus reducing the residual protection of the acaricide as well as increased tick activity during the wet season thus increasing disease challenge. Consequently, this period constitutes the most risk period hence critical for insurance in which the effectiveness of mitigation measures taken by the producer are evaluated. For instance,  it is recommended that frequency of dipping/spraying and acaricide replenishment (top up) be enhanced during wet seasons to mitigate increased disease challenge (Gachohi et al 2011). For purposes of livestock insurance, other than looking at morbidity of East Coast fever per se, it is equally important to look at the underlying factors to morbidity such as level of tick challenge, dipping frequency, dip wash sampling and analysis, as well as dip wash replenishment frequency. Both farm A and B had low incidences of East Coast fever of 0.0100 and 0.00909, respectively. This could be attributed to the restricted animal movement and contact of animals with external parties (both humans and animals) as well as strict adherence to dipping/ spraying routines. These farms had effective movement barriers to control animal movements and human entry into and exit from the farms. Elsewhere, studies have revealed higher prevalence of East Coast fever in extensive grazing systems than in intensive systems (Gichohi et al 2011; 2012; Rubaire-Akiiki et al 2004). Though these farms had large expenses for prophylactic management, their curative expenses were minimal. The relative cost of herd curative management of East Coast fever per animal was KES 64 and KES 47.3 in farm A and B, respectively (Table 3 and Table 4).

In endemic areas, East Coast fever has been associated with high mortalities (Gitau et al 2000). Revenue losses from East Coast fever are however not only limited to mortalities but also from drop in milk production from sick animals and total loss of milk during the withdrawal period in animals on treatment. This study was only able to estimate costs associated with animal mortality and loss of milk sales during the withdrawal period. Consequently, the values of revenue losses could be slightly underestimated since one component (drop in milk production for the theileria infected animals) was not included. This component could not be included due to the difficulty by the farms to ascertain the infection time which is critical in determining the incubation period of the disease and convalescence which was highly varied between animals. Revenue losses were least in farm B (Table 4). This could be attributed to the low morbidity in this farm resulting in only KES 239.290 loss in milk revenue during the withdrawal period (Table 3). Animals in Farm A and B were of good pedigree and high milk producers, therefore, though morbidity and mortality were low, a single disease incident or death had over reaching effects on farm profitability as compared to the would be effect in low producing animals. Due to their high productivity and pedigree, these animals fetched high market prices as breeding animals in other farms. Kahi and Nitter (2004) and Kahi et al (2004) reported milk production and sale of breeding stock as the key revenue sources of dairy production systems with resultant high economic values for milk productivity and fertility traits.

Conclusions

• This procedure has successfully estimated the costs of East Coast fever management using the variable factors on the farm.
  
  
• It easily lends itself to expansion to include factors that influence fixed costs of East Coast fever management such as physical infrastructure like dips or spray races on the farm and could be used with modifications for valuation of other diseases. Other than finding use in computation of disease impacts on the farm, it could be used by livestock insurance agencies and compensation schemes in computation of premiums and determination of compensation of losses.
  
  
• The effectiveness of managing East Coast fever depends largely on prophylactic management.
  
  
• Costs of curative management and revenue losses will consequently escalate in farms where prophylactic management practices are weakly enforced.
  
  
• Given the negative correlation between productive traits and disease resistance, disease management for high yielding animals should be strongly enforced to mitigate heavy revenue losses attributed to either animal deaths or milk sales.
  
  
• When insuring animals firms should not only look at the animal characteristics but also the farm characteristics that influence disease morbidity as well as animal mortality.

References

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Received 27 January 2015; Accepted 27 July 2015; Published 1 October 2015

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